140 ' Aiiaiyaes of Books, [Auc. 



beneath the tent, were then pointed, two on the station of La 

 Canche, and two on that of Wrotham Hill. Those directed to 

 the former were of four inches clear aperture, the others of 

 three. In case of any difficulty arising as to the pointing, I 

 had taken care to provide myself with an excellent eight-inch 

 repeating theodolite, on the Reichenbach construction, by 

 Schenck, of Berne ; but it was found unnecessary to use it, as 

 the night glasses were purposely constructed with an azimuthal 

 motion, and a rough graduation read off by an adjustable ver- 

 nier, so as to allow their being set at once a few minutes before 

 the observations commenced, by taking Fairlight steeple as a 

 zero point ; a circumstance which proved exceedingly conve- 

 nient, as it allowed of their being dismounted after each night's 

 observations, and removed to a place of security ; and thus 

 rendering it unnecessary to harass our small party by keeping 

 guard in our absence. 



" On the night of the 8th I had directed blue lights to be fired 

 at Wrotham, as atrial of the visibility of the stations, or rather 

 as a verification of the pointing of the telescopes ; for on the 

 former point there could be no doubt, the station at Wrotham 

 being situated precisely on the edge of the escarpment of the 

 chalk which borders the Weald of Kent, and having been actually 

 connected with Fairlight by direct observation, while no ob- 

 stacle but a low copse wood, over which it might fairly be 

 presumed that no rocket would fail to rise, separated it from a 

 direct view of Greenwich, at about 20 miles distance. Either 

 from haze in the atmosphere, or from the too great distance, 

 nothing was seen that night or the next ; which however caused 

 no uneasiness, as we could depend on our instruments and 

 information. The next morning Capt. Sabine quitted Hastings, 

 and joined Col. Bonne, at his post, on the morning of the 10th, 

 the day appointed for the commencement of the observations ; 

 meanwhile I was joined by M. Largeteau, who remained with 

 me the whole time of their continuance, performing every part 

 of a most scrupulous and exact observer, as the observations 

 herewith communicated will abundantly testify. 



** The observations were continued during 12 nights, 10 signals 

 being made at each rocket station every night. The weather 

 throughout the whole of this time was magnificent, and such as 

 is not very likely to occur again for some years ; a circumstance 

 of the last importance in operations of this nature, where lights 

 are to be seen across nearly oU miles of sea, and also by reason 

 of the verification of the sidereal times at the observatories by 

 transits. One night only a local fog deprived us of the sight of 

 13 out of the 20 signals ; but on the whole, out of 120 made at 

 Wrotham, no less than 112 were seen from Fairlight (about 40 

 miles) and 89 from Greenwich ; while out of the same number made 

 at La Canche, 93 were observed attjie former post. I am sorry to 



